Ensure this works with Ruby 3.0.0 by adding the #attribute method within any class to extend ActiveRecord in order to create those helper methods.
Example:
class Company < ActiveRecord::Base include AcceptsNestedIds has_many :users accepts_nested_ids_for :users attribute :user_ids end
Ensure empty array of nested associations is loaded, to handle situations where a sub class does not define its own associations and the intersection between base and sub class associations was failing.
Fix for associations defined on a subclass not being saved.
Fix for STI.